I don't know what Sam is talking about, but you can totally use that flash. At the minimum you need a wired connection, but much better to use a wireless trigger. Some of those are very expensive, but there are pretty cheap ones too that work great. I have one I'm very happy with, but I'll need to look it up. There are ones that also take advantage of your Canon's E-TTL, but I'm mot sure how reliable that is with this use. If you want to dive into it more, Yongnuo has some really awesome flash gear. With the more basic ones, you can trigger and adjust the output of multiple flashes from the camera, and I think they now also have ones that incorporate E-TTL. One problem is, I had to laugh at the comment in that video that two speedlights are "almost as powerful as studio strobes." Not... even... close. Competing with daylight with these little portable setups won't be easy. So don't expect to do miracles. Functionally, there is nothing different about those MagBox items than a dozen other kinds available. They've just designed them to be smoother to work with. And they do look like they're nicely designed, but as far as what they can do, they are not remotely anything new.